The Planisphere

This OER was designed by the OU Academy of the Lynx (oulynx.org) in conjunction with the "Galileo's World" (galileo.ou.edu) exhibition at the University of Oklahoma.

This activity is designed to be completed in 5 minutes by a typical visitor to the exhibition. For adaptations to other age levels and pedagogical settings, visit the "Planisphere Educational Cluster" below.

Introductory Planisphere Activity

The planisphere is a handy map of the night sky that works every night, every season of the year.

** The only supply necessary to complete this activity is a planisphere. We suggest this one if you do not already have one, www.astronomics.com/datalizer-miller-10-5-inch-30-degree-planisphere-25-35-degrees-n_p3678.aspx. **

1. Examine your planisphere, front and back. Note that constellations are labelled in ALL CAPS with a large font; bright stars or asterisms are labelled in lower case with a smaller font.
2. Times are indicated on the planisphere in Standard time.  From April to October add 1 hour to obtain Daylight Savings Time (DST).  Remember that DST is one hour later than the Standard time the planisphere indicates.
3. Find Sagittarius the Archer and Scorpius the Scorpion on the planisphere, turning the inside dial as needed.  On what date will Sagittarius and Scorpius be easily visible at 9 pm? 
4. Set the planisphere to 9 pm this evening. 
5. Find the north, south, east and west horizons on the planisphere. First find north (designated by an arrow), then the other cardinal directions ("never eat slimy worms").
6. Position yourself so that you face south. Star charts are usually designed for facing due south, optimized for about half-way up from the horizon.
7. Read road maps looking down, but read star charts looking up. Hold the planisphere above your head so that the north arrow points north.
8. What constellations will be visible in the sky tonight?

Enjoy a downloadable pdf of this activity:

Historical Background for the Planisphere

The planisphere is a handy map of the night sky that works every night, every season of the year. During the time of Galileo, in the 16th and 17th centuries, planispheres were a common astronomical instrument. It was useful for calculating the positions of the stars for any day and hour of the year. 

A contemporary of Galileo, William Schickard developed a planisphere, also known as an "astroscopium" to help calculate the position of the planets. Read more about Schickard's astroscopium on the Galileo's World website, galileo.ou.edu/node/1744.

Or download these high-quality images from his 1698 book, courtesy History of Science Collections, University of Oklahoma Libraries.

Further OER's on the Planisphere

Use the following OER's to further explore the planisphere.

• "Planisphere" from Wikipedia, en.wikipedia.org/wiki/Planisphere.
• "Planisphere" from Museo Galileo website, catalogue.museogalileo.it/indepth/Planisphere.html.
• "How to Use a Planisphere" by Sierra College Astronomy Department, astronomy.sierracollege.edu/Courses/Astronomy10/Planisphere.htm.
• "Virtual Planisphere" by Ernie Wright, www.etwright.org/astro/plani.html.

Use the following OER's to further explore the Galileo's World exhibition.

• Galileo's World iPad Exhibit Guide, itunes.apple.com/us/book/galileos-world-exhibit-guide/id1032005948?mt=1.
• Galileo's World iTunes U Course, itunesu.itunes.apple.com/enroll/FDS-EYK-MRL.
• Galileo's World website, galileo.ou.edu.

Planisphere Educational Cluster

We want to create variations on this activity that connect the Planisphere to a variety of ages. Use the following chart and hyperlinks to find the one to best fit your group.